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March 29, 2024, 06:49:25 pm

Author Topic: VCE Biology Question Thread  (Read 3571441 times)  Share 

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MM1

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Re: VCE Biology Question Thread
« Reply #360 on: January 28, 2014, 07:47:11 pm »
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According to my textbook, useful molecules diffuse back into the cytoplasm from the lysosome. How is this possible?

Also, how do the hydrolytic enzymes in the lysosomes break down foreign debris when the enzyme and substrate are meant to be specific?

Thanks :)

Basically what Chang Feng said, some of these molecules, when broken down, can be used again by the cell so therefore they are retained. Perhaps by exocytosis if you mean how.

As for your second question, I believe the enzyme is able to slightly change its shape as the substrate binds on to it. Even though they aren't the same structurally they are similar. Think of the Induced Fit theory here, where the enzyme locks onto the substrate at its active site by slightly changing shape.
« Last Edit: January 28, 2014, 07:54:17 pm by MM1 »

MM1

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Re: VCE Biology Question Thread
« Reply #361 on: January 28, 2014, 07:51:23 pm »
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I was just wondering for the disease chapter, what are we required to know about each different agent/ pathogen- (eg there name, function)? thanks.

According to the SD, we're required to know about cellular and non-cellular agents such as viruses and prions. I think we just need to know what they are and their function and features and what effect they might impose if having affected someone. Knowing a few diseases isn't required but I think it would be good to know.

Chang Feng

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Re: VCE Biology Question Thread
« Reply #362 on: January 28, 2014, 08:00:37 pm »
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so if enzymes can change as represented by the induced fit model, does that mean technically all substrates are similar to the enzyme since their would be a variety of different complex molecules with different binding sites which need to be broken down by enzymes. wait, or is it there are many different enzymes in the lysosome with various active sites?
and thanks too.

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Re: VCE Biology Question Thread
« Reply #363 on: January 28, 2014, 08:06:14 pm »
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so if enzymes can change as represented by the induced fit model, does that mean technically all substrates are similar to the enzyme since their would be a variety of different complex molecules with different binding sites which need to be broken down by enzymes. wait, or is it there are many different enzymes in the lysosome with various active sites?
and thanks too.

There are different ways in which an enzyme binds to a substrate. As MM1 mentioned, the induced fit model is an example in which coenzymes enable the enzyme to fit the substrate. The lock and key model is another method in which the enzyme accurately fits the substrate.
In the case of lysosomes, I'm guessing most of the binding between enzyme and substrate is similar to the induced fit model since the hydrolytic enzymes break down foreign and unwanted debris therefore if the binding were specific, then the enzyme may not be able to break down other unwanted substances.

MM1

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Re: VCE Biology Question Thread
« Reply #364 on: January 28, 2014, 08:12:26 pm »
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so if enzymes can change as represented by the induced fit model, does that mean technically all substrates are similar to the enzyme since their would be a variety of different complex molecules with different binding sites which need to be broken down by enzymes. wait, or is it there are many different enzymes in the lysosome with various active sites?
and thanks too.

I wouldn't say all substrates are similar to the enzyme - it's their active site which is similar in structure.
Maybe there are many different enzymes in the lysosome with various active sites however I think the fact that the enzymes can alter their shape (induced fit theory) is what metabolises the reactions.


scribble

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Re: VCE Biology Question Thread
« Reply #365 on: January 28, 2014, 08:20:42 pm »
+1
hydrolytic enzymes are a broad term used to describe enzymes that break biomolecules down into smaller components by hydrolysis.
there are many, many different types of hydrolytic enzymes contained within a lysosome . proteases for example break hydrolyse the peptide bond that links individual amino acids together in proteins, and nucleases break the phosphodiester bond between nucleotides in dna.
and then under those categories, there are specifics as well. Some proteases may only cleave the protein at a specific amino acid for example. (you needn't worry about this at vce level)

alondouek

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Re: VCE Biology Question Thread
« Reply #366 on: January 28, 2014, 08:44:38 pm »
+2
so if enzymes can change as represented by the induced fit model, does that mean technically all substrates are similar to the enzyme since their would be a variety of different complex molecules with different binding sites which need to be broken down by enzymes. wait, or is it there are many different enzymes in the lysosome with various active sites?
and thanks too.

Acid hydrolases (the type of enzyme in lysosomes) come in many different forms. As with all of biology, form leads to function and therefore differences in form lead to differences in function. Acid hydrolases of varying form can be proteases, glycosidases, lipases etc (i.e. they can break down a wide range of molecules because they have a wide range of structures)
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katiesaliba

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Re: VCE Biology Question Thread
« Reply #367 on: January 29, 2014, 01:35:19 pm »
+1
Hi guys, wondering if you could help me out with a few questions I have!

1)Are conjugated proteins counted as a part of the protein’s quaternary structure?
2)Are lipids made up of chains of glycogen and fatty acids? Or are fatty acids and glycerols arranged in some other form?
3)Are proteins in the plasma membrane only of the quaternary structure?
4)Does tRNA only have three bases in its sequence? The photo attached is the concerned question from my textbook
Thank you! :)
« Last Edit: January 29, 2014, 08:40:16 pm by katiesaliba »
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elsalouise123

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Re: VCE Biology Question Thread
« Reply #368 on: January 29, 2014, 03:10:48 pm »
+1
hey all you mad Biologist's!
Just wondering what the best way to study for this subject ( in particular all you 40 and > scores!!)

Is it viable to type notes in class and then go home and write notes out with other sources as per study design???

Your knowledge would be greatly appreciated. thanks

alchemy

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Re: VCE Biology Question Thread
« Reply #369 on: January 29, 2014, 07:11:46 pm »
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Hi guys, wondering if you could help me out with a few questions I have!

1)Are conjugated proteins counted as apart of the protein’s quaternary structure?
2)Are lipids made up of chains of glycogen and fatty acids? Or are fatty acids and glycerols arranged in some other form?
3)Are proteins in the plasma membrane only of the quaternary structure?
4)Does tRNA only have three bases in its sequence? The photo attached is the concerned question from my textbook
Thank you! :)

1) Do you mean "as a part*" instead of "as apart"? If you do, you should know that not all conjugated proteins are considered to have quarternary structure. Collagen is an example of a conjugated protein that does have a quarternary structure. Conjugated proteins have a prosthetic group (non-protein part) attached to them, meaning upon hydrolysis they would yield another chemical component other than amino acids.
2) Lipids aren't linked together to form 'chains of glycogen and fatty acids'. Proteins are examples of long chains of amino acids as evident in their primary structure. Lipids have smaller molecules that aren't exactly structured in the form of repetitive chains.
3) I think you mean "do proteins in the plasma membrane have a quarternary structure?", as proteins cannot only have a quarternary structure! So, not all membrane proteins have a quarternary structure. I believe most of them have tertiary structures.
4) RNA has 4 bases in general. It's just that Thymine from DNA is replaced by Uracil in RNA. So RNA would have Adenine, Uracil, Guanine and Cytosine.
As for the photo, it won't be possible to tell what type of RNA it is, unless we know its function. Hope that helps, and as always, someone please correct me if I was incorrect on any of the above.

MagicGecko

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Re: VCE Biology Question Thread
« Reply #370 on: January 29, 2014, 07:27:40 pm »
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hey all you mad Biologist's!
Just wondering what the best way to study for this subject ( in particular all you 40 and > scores!!)

Is it viable to type notes in class and then go home and write notes out with other sources as per study design???

Your knowledge would be greatly appreciated. thanks

Everyone has their own techniques in studying biology. I never really liked typing out notes, too troublesome, especially with diagrams. I had a lecture pad which I would copy down the notes in class. I would then go home and re write those notes in my biology notebook. I found writing down the info twice helped me remember it better. Also drawing a lot of pictures helped me :P
It may also help if you have access to two textbooks, because some textbook are more detailed than others. Listening to Douchy's biology podcast's was quite good if I remember correctly, sure did help in the immunity part.
 
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MagicGecko

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Re: VCE Biology Question Thread
« Reply #371 on: January 29, 2014, 07:40:07 pm »
0
Hi guys, wondering if you could help me out with a few questions I have!

1)Are conjugated proteins counted as apart of the protein’s quaternary structure?
2)Are lipids made up of chains of glycogen and fatty acids? Or are fatty acids and glycerols arranged in some other form?
3)Are proteins in the plasma membrane only of the quaternary structure?
4)Does tRNA only have three bases in its sequence? The photo attached is the concerned question from my textbook
Thank you! :)

Branching off on what alchemy said about 2)
If lipids were made up of 'chains' of glycogen and fatty acids, this would make them the monomer of lipids, however lipids don't have a monomer. Instead you refer to them as sub-units and no, they don't make 'chains'.
 
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katiesaliba

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Re: VCE Biology Question Thread
« Reply #372 on: January 29, 2014, 09:07:54 pm »
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1) Do you mean "as a part*" instead of "as apart"? If you do, you should know that not all conjugated proteins are considered to have quarternary structure. Collagen is an example of a conjugated protein that does have a quarternary structure. Conjugated proteins have a prosthetic group (non-protein part) attached to them, meaning upon hydrolysis they would yield another chemical component other than amino acids.
2) Lipids aren't linked together to form 'chains of glycogen and fatty acids'. Proteins are examples of long chains of amino acids as evident in their primary structure. Lipids have smaller molecules that aren't exactly structured in the form of repetitive chains.
3) I think you mean "do proteins in the plasma membrane have a quarternary structure?", as proteins cannot only have a quarternary structure! So, not all membrane proteins have a quarternary structure. I believe most of them have tertiary structures.
4) RNA has 4 bases in general. It's just that Thymine from DNA is replaced by Uracil in RNA. So RNA would have Adenine, Uracil, Guanine and Cytosine.
As for the photo, it won't be possible to tell what type of RNA it is, unless we know its function. Hope that helps, and as always, someone please correct me if I was incorrect on any of the above.

Thanks so much!
So building on question 2), what kind of forces hold lipids together?
For question 3), I meant what I said. I had encountered a question earlier asking if membrane proteins were only of a quaternary structure  :P I think I've just presumed that quaternary structured proteins are more common than their tertiary counterparts.
With question 4), I'm still confused as to why all RNA looks the same. I know that RNA has four different nitrogenous bases, but isn't the RNA sequence in each tRNA just 3 bases? Concerning the picture, why is it impossible to differentiate between RNA types when tRNA has a base sequence of 3 nitrogenous bases? I'm missing something about the structure of tRNA! :-\
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MagicGecko

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Re: VCE Biology Question Thread
« Reply #373 on: January 29, 2014, 09:44:12 pm »
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The hydrophobic tails are held together by 'Van der Waals' forces whereas 'hydrogen bonds' is the force that holds hydrophilic heads together as well as interact with water, therefore helping to stabilize the phospholipid bilayer structure.

Concerning the picture, why is it impossible to differentiate between RNA types when tRNA has a base sequence of 3 nitrogenous bases?




This picture might help. Basically tRNA doesn't have just 3 nitrogen bases, in actual fact it has many, its just that the 3 you assumed it only had are the only anti-codons (hence why some diagrams normally just display those three bases since those are the only 'important' ones).
The only way you would be able to distinguish what type of RNA it is would be if the question added something like 'this RNA also codes for 6 amino acids', in which case it would be mRNA, because mRNA is the only one out of the three which is translated into a polypeptide.
« Last Edit: January 30, 2014, 02:42:06 am by MagicGecko »
 
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Re: VCE Biology Question Thread
« Reply #374 on: January 29, 2014, 09:48:57 pm »
+2
You can stipulate the size of the image by using [img width=insert number here (e.g. 500)]insert image URL here[/img]
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